Heat exchanger

ABSTRACT

A heat exchanger for exchanging heat between a cooler first air flow and a warmer second air flow is disclosed. The heat exchanger comprises a heat exchanger unit having a housing containing a plurality of heat exchanger plates stacked together to form a stack. Each heat exchanger plate has four corners and an aperture located adjacent each comer, the heat exchanger plates being dimensioned and configured such that the apertures of the heat exchanger plates overlap to form a first, second, third and fourth air passageways in the stack. The heat exchanger plates are further configured to form an alternating series of first and second flat parallel air chambers in the stack, the first set of air chambers being continuous with the first and second air passages such that air can pass between the first and second air passages through the first set of air chambers, the second set of air chambers being continuous with the third and fourth air passageways such that air can pass between the third and fourth air passageways through the second set of air chambers. The stack of heat exchanger plates are further configured such that the first and second set or air chambers are substantially air tight such that air does not leak between the first and second set of air chambers. The heat exchanger unit has a first and second side, the first, second, third and fourth air passageways each having a first end open to the first side of the heat exchanger unit at a first port and an opposite second end opened to the second side of the heat exchanger unit at a second port. The stack is further adapted such that each port may be selectively plugged by a plug member, the heat exchanger unit having four plug members, each plug member plugging one end of each air passageway. Finally, the first, second, third and fourth air conduits, are each operatively coupled to one of the air passageways, the air conduits carrying the first and second air flows.

FIELD OF THE INVENTION

[0001] The invention relates generally to the field of heat exchangersfor exchanging heat between cold air and heated air.

BACKGROUND OF THE INVENTION

[0002] Countercurrent heat exchangers are well known. They generallyconsist of a housing having a plurality of heat exchanger plates whichseparate a first flow of fluid from a second flow of fluid. The heatexchanger plates generally consist of substantially flat plates which,while keeping the first and second flows separate, bring both flows insufficiently close proximity to permit heat to be exchanged between thetwo flows.

[0003] Countercurrent heat exchangers are presently used in severalapplications, however, their use in residential and commercial buildinghas been limited by their high cost. Heat exchanger plates are usuallywelded or bonded together using expensive and time consuming techniques.Furthermore, present day heat exchangers are difficult to integrate intomodern forced air heating and air conditioning systems. Finally, due totheir expense and complexity of design, existing heat exchangers aredifficult to customize. in most cases, a heat exchanger requires theinstaller little flexibility in duct positioning; thereby decreasing itsappeal to builders. A simplified, low cost and flexible heat exchangersystem would be easier to sell to the residential and commercialconstruction industries.

SUMMARY OF THE INVENTION

[0004] The present invention is a heat exchanger for exchanging heatbetween a cooler first air flow and a warmer second air flow. The heatexchanger comprises a heat exchanger unit having a housing containing aplurality of heat exchanger plates stacked together to form a stack.Each heat exchanger plate has four corners and an aperture locatedadjacent each comer, the heat exchanger plates being dimensioned andconfigured such that the apertures of the heat exchanger plates overlapto form a first, second, third and fourth air passageways in the stack.The heat exchanger plates are further configured to form an alternatingseries of first and second flat parallel air chambers in the stack, thefirst set of air chambers being continuous with the first and second airpassages such that air can pass between the first and second airpassages through the first set of air chambers, the second set of airchambers being continuous with the third and fourth air passageways suchthat air can pass between the third and fourth air passageways throughthe second set of air chambers. The stack of heat exchanger plates arefurther configured such that the first and second set or air chambersare substantially air tight such that air does not leak between thefirst and second set of air chambers. The heat exchanger unit has afirst and second side, the first, second, third and fourth airpassageways each having a first end open to the first side of the heatexchanger unit at a first port and an opposite second end opened to thesecond side of the heat exchanger unit at a second port. The stack isfurther adapted such that each port may be selectively plugged by a plugmember, the heat exchanger unit having four plug members, each plugmember plugging one end of each air passageway. Finally, the first,second, third and fourth air conduits, are each operatively coupled toone of the air passageways, the air conduits carrying the first andsecond air flows.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005]FIG. 1. Is a perspective view of a heat exchanger of the presentinvention.

[0006]FIG. 2. Is a top view of a heat exchanger panel of the presentinvention.

[0007]FIG. 3. Is a cross sectional view of the heat exchange panel shownin FIG. 2 taken along line A-A.

[0008]FIG. 4. Is a long sectional view of the heat exchanger unit shownin FIG. 1 taken along line B-B.

[0009]FIG. 5. Is a long sectional view of the heat exchanger unit shownin FIG. 1 taken along line C-C.

[0010]FIG. 6. Is a cross sectional view of a portion of an airpassageway section of a heat exchanger of the present invention whereinthe air passageway has not yet been sealed.

[0011]FIG. 7. Is a cross sectional view of the portion of the heatexchanger unit shown in FIG. 6 wherein the passageway has been sealed.

[0012]FIG. 8. Is a top view of an alternate embodiment of the heatexchanger panel.

[0013]FIG. 9. Is a cross sectional view of the heat exchanger panelshown in FIG. 8 taken along line F-F.

[0014]FIG. 10. Is a cross sectional view of a portion of an airpassageway section of a heat exchanger in accordance with an alternateembodiment of the present invention wherein the air passageway has notyet been sealed.

[0015]FIG. 11. Is a cross sectional view of the portion of the heatexchanger unit shown in FIG. 10 wherein the passageway has been sealed.

[0016]FIG. 12. Is a front view of two heat exchangers made in accordancewith the present invention being mounted on the roof of a building.

DETAILED DESCRIPTION OF THE INVENTION

[0017] Referring firstly to FIG. 1, a heat exchanger system, showngenerally as item 10, can be used to transfer the heat from the internalair of a building to the external air outside of the building as theinternal air is exhausted out of the building and the cooler outside airis vented into the building. A heat exchanger system made in accordancewith the present invention consists of a heat exchanger unit 12 mountedbetween exhaust conduits 14 and intake conduits 16. Exhaust conduit 14consists of parallel conduits 18 and 20 while intake conduit 16 consistsof parallel conduits 22 and 24. Heat exchanger 12 consists of aplurality of heat exchanger units 26, each of which is formed from aplurality of heat exchanger plates 28. Heat exchanger unit 26 hasconduit 30 for receiving warm stale air from conduit 18. Heat exchangerplates 28 channels the warm stale air from conduit 30 into oppositeconduit 32 located on the other side of the heat exchanger plates. Airfrom conduit 32 is exhausted into conduit 20 via a fan or other meansknown in the art.

[0018] Heat exchanger unit 26 is also provided with conduits 34 whichreceives air from conduit 24. Air from conduit 34 is channeled throughheat exchanger plates 28 to conduit 36 at the opposite end of plates 28.Conduit 24 is open to the outside of the building, and is thereforefilled with cooler fresh air. Cooler fresh air is forced into conduit 24by a fan or other means and makes its way into conduit 34. Conduit 34distributes the cooler fresh air through plates 28, which exhaust intoconduit 36. Conduit 36 in turn exhausts into conduit 22 which suppliesthe inside of the building with fresh air. As warm stale air from insidethe building is forced through conduit 18 via a fan or other means, itpasses through conduit 30 and out conduit 32 where it is in turn passedto conduit 20 and is exhausted out of the building. As the air passesfrom conduit 30 to 32, it passes through plates 28. Likewise, as airpasses through conduit 34 to conduit 36, it passes through plates 28.For the purposes of this patent application, the air flow from conduit30 to 32 will be referred to as the outgoing air flow, and the air flowfrom conduit 34 to 36 will be referred to as the ingoing air flow. Aswill be explained in greater detail, plates 28 are adapted andconfigured to separate the ingoing and outgoing air flows into separateingoing and outgoing air channels. These separate air channels arearranged such that the ingoing and outgoing air flows travel in parallelbut opposite directions through plates 28. As will be explained ingreater detail, plates 28 are further configured such that the ingoingand outgoing air channels are in thermal contact, such that a portion ofthe heat contained in the warmer air of the outgoing air channels istransferred to the cooler air of the ingoing air channel. In this way,warm stale air from the inside of a building may be used to heat coldfresh air which is pumped into the building.

[0019] The capacity of heat exchanger plate 10 can be increased simplyby increasing the number of heat exchanger units 26. Hence, if the heatexchanger capacity of heat exchanger 10 is to be increased, additionalheat exchanger units 26 are mounted between conduits 14 and 16.

[0020] Referring now to FIG. 2, each heat exchanger plate 28 consists ofa substantially flat metal plate having a flat surface 38, opposite ends40 and 42, and opposite sides 44 and 46. Surface 38 is provided with apair of apertures 48 and 50 towards opposite ends 40 and 42. Aperture 50is provided with corrugated rim 52 which assists in the formation of anair passageway. Preferably, apertures 48 and 50 located at end 40 are inopposite orientation to apertures 48 and 50 located towards end 42.

[0021] Referring now to FIG. 3, corrugated rim 52 surrounding aperture50 consists of outside wall 58, top 68, middle wall 56, lower portion 62and inner wall 60. Inner wall 60, bottom portion 62 and middle wall 56are formed such that inner gap 64 is created separating walls 56 and 60.Likewise, outer walls 58 and middle wall 56 are separated by gap 70.Aperture 48 is defined by horizontal wall 72 having shoulder 71 and lip54. Wall 72 is substantially perpendicular to surface 38. Side 44 formsan angular wall rising perpendicularly from surface 38. Likewise, side46 forms an angular wall having top surface 76 rising perpendicularlyfrom surface 38.

[0022] Turning now to FIGS. 4 and 5, each heat exchanger unit 26 isformed from a plurality of heat exchanger plates 28 which are stackedone on top of the other within housing 80 such that apertures 48 of oneheat exchanger plate is alined with aperture 50 of the heat exchangerplate immediately below. Apertures 48 and 50 of heat exchanger plates 28form air conduits 34, 30, 32 and 36. Heat exchanger plates 28 also formair chambers 84 and 82 which are separated by heat exchanger surfaces38. Due to the sealing arrangement between apertures 48 and 50, conduit34 is continuous with chambers 82 while conduit 30 is continuous withchambers 84. Conduit 34 is sealed at one end by cap 96 and conduit 30 issealed at one end by cap 90. As air travels through conduit 34 ittravels through air chambers 82 and out of air conduit 36. Likewise, asair travels through conduit 30 it travels into chambers 84 and out ofconduit 32. Surfaces 38 of heat exchanger plates 28 separate the airflow in chambers 82 and 84. It will be appreciated that the air inchamber 82 is flowing in a parallel but opposite direction to the air inchambers 84. Since heat exchanger plates 28 are made of aluminum orsheet metal or some other such material, heat is exchanged betweenchambers 82 and 84 in a counter flow arrangement.

[0023] One of the advantages of the present heat exchanger plate designis that by simply capping different apertures, a different pattern ofair flow can be created in the heat exchanger unit. For example,considering the embodiment shown in FIGS. 4 and 5, heat exchanger unit12 has eight possible ports through which air may pass into or out ofthe heat exchanger unit. In particular, heat exchanger unit 12 has ports86 a, 86 b, 92 a, 92 b, 94 a, 94 b, 88 a and 88 b. These ports caneither be left opened or closed, depending on the particular air flowpattern desired. In the particular example shown in FIGS. 4 and 5, ports86 a, 92 b, 88 a and 94 b are left open, while ports 92 a, 86 b, 94 aand 88 b are closed off by caps 90 and 96. This particular arrangementof open and closed ports permits a first airflow D between ports 86 aand 88 a and a second air flow E between ports 94 b and 92 b. If firstairflow D represents the ingoing air flow and second airflow Erepresents the outgoing air flow, then cold fresh air would flow intoport 86 a, pick up heat from airflow E and then exhaust as warmer freshair out of port 88 a. Likewise, warmer stale air would enter port 92 b,exchange its heat with air flow D, and exhaust as cooler stale air outport 94 b. By capping different ports, a different air flow pattern canbe created. For example, by capping ports 88 a and 94 b and openingports 88 b and 94 a, a different counter current air flow pattern iscreated.

[0024] It will be appreciated that depending on the needs of thecustomer, certain air flow patterns may be more desirable than others.The particular arrangement shown in FIG. 1 shows fresh air being carriedby conduits 24 and 22 of intake conduits 16 while stale air is carriedin conduits 18 and 20 of exhaust conduit 14. In some applications, thisparticular arrangement may not be optimal since there will be atemperature difference between conduits 24/22 and conduits 18/20. insome applications, this may result in condensation build up. Ifcondensation buildup is a problem, it may be preferable to keep both ofthe “warm” air flows together in the same intake or exhaust conduit. Theversatility of the present design permits each heat exchanger unit to becustomized to meet particular applications. All that is required toalter the internal air flow pattern is a number of caps 90 and 96. Inthis way, each heat exchanger can be tailored to the specific needs ofthe customer.

[0025] Referring now to FIG. 6, the method of sealing heat exchangerplates 28 will now be disclosed. The inside diameter of aperture 48 isselected such that lip 72 of first heat exchanger plate 98 can fitbetween middle wall 56 and inner wall 60 of lower heat exchanger plate100. Surfaces 38 of heat exchanger plates 98 and 100 define chamber 102.The height of walls 58 and 56 define the height of chamber 102. Outerwall 58 and middle wall 56 form a rigid annular structure which supportsheat exchanger plate 98. Aperture 48 is dimensioned such that lip 72fits within gap 64 defined by middle wall 56 and inner wall 60 of heatexchanger plate 100. Inner wall 60 is dimensioned such that lip 66projects above surface 38 of heat exchanger plate 98.

[0026] As seen in FIG. 7, plate 98 and 100 are sealed together such thatrelatively little air leaks from chamber 102 into aperture 50. Thesealing is accomplished by deforming inner wall 60 and adjacent lip 66such that lip 66 makes contact with shoulder 71 of upper heat exchangerplate 98. To ensure that lip 66 makes contact with shoulder 71 all alongthe periphery of aperture 50, lip 72 is selected to be sufficiently longsuch that rim 54 of lip 72 makes contact with lower portion 62 of lowerheat exchanger plate 100. This structure permits lip 72 to resist theforce of the tool which is used to deform edge 66 against shoulder 71.It has been discovered that if edge 54 of lip 72 does not make contactwith bottom portion 62, then a tight seal between shoulder 71 and edge66 is less likely to occur.

[0027] An alternate embodiment of the heat exchanger plates of thepresent invention is shown in FIGS. 8, 9, 10 and 11. The alternateembodiment essentially consists of an alternate structure for thesealing of the heat exchanger plates. As seen in FIG. 8, heat exchangerplate 150 consists of a substantially flat metal plate having flatsurface 152 opposite ends 154 and 156 and opposite sides 158 and 160.Flat surface 152 is provided with a pair of apertures 162 and 164 towardend 154 and apertures 166 and 168 toward end 156. Apertures 164 and 166are provided with rim 170 and 172, respectively.

[0028] Referring now to FIG. 9, rim 172 consists of a cone like base 176surrounding a cylindrical collar 174. Base 176 is at an angle (alpha)relative to flat surface 152. Collar 174 is at an angle beta to base176. It will be appreciated that base 176 consists of a cone-like baseextending outwardly from collar 174. Collar 174 has an upper rim 182which defines the diameter of opening 166. Base 176 and collar 174 aredimensioned such that rim 182 projects above ledges 178 and 180.Aperture 162 is formed on flat surface 152 as a simple aperture havingrim 176. The diameter of aperture 162 is slightly higher than theoutside diameter of collar 174. Preferably, aperture 162 isapproximately 20 thousandth in radius larger than the outside diameterof collar 174.

[0029] Referring now to FIGS. 10 and 11, heat exchanger plates 150 canbe stacked one on top of the other as in the previous embodiment. Whenheat exchange plates 150 are stacked one on top of the other, aplurality of parallel air chambers 188 and 190 are formed. An airpassage way connecting air chambers 190 is formed by openings 166, andbase 176. Collar portion 174 of a lower heat exchanger plate is insertedinto aperture 162 of a corresponding upper heat exchanger plate suchthat collar portion 174 pass through aperture 162, as shown in FIG. 10.To seal the gap separating rim 196 from collar 174, collar 174 is bentaround rim 196 as shown in FIG. 11. Angle alpha is selected to ensurethat collar 174 can be deformed to seal aperture 162 without causingflat surfaces 152 to deform. It has been discovered that if angle alphaequals 38 degrees or less, and if collar 174 is approximately 0.03inches in height between rim 182 and point 184 where the collar meetsbase 176, then wall 174 may be bent around rim 196 of aperture 162without causing any significant deformation of flat surface 152.Experiments using aluminum 50-52 sheeting having a thickness of 0.02inches, showed that an angle alpha of 38 degrees permitted tight sealingof aperture 162 without significant buckling of surface 152. Bycontrast, when Alpha angles of 40 degrees or 42 degrees were attempted,significant buckling of flat surface 152 occurred. Furthermore, wherealpha was greater than 38 degrees, very poor ceiling around rim 196 wasobtained.

[0030] As mentioned previously, one of the advantages of the presentinvention is how the air flow patterns in the heat exchanger can bemodified to suit the particular needs of the customer. This isparticularly evident when two heat exchangers are to be coupled for highvolume applications. Referring now to FIG. 12, if building 200 requiresa higher capacity of fresh air ventilation, then two heat exchangers,104 and 106 may be mounted to roof 202. In order to ensure that only onehole is made in the roof to accommodate the exhaust ducts, exhaustconduit 108 of heat exchanger 106 and exhaust conduit 110 of heatexchanger 104 can be arranged such that the two exhaust conduits areside by side. This side by side arrangement permits the exhaust conduitsof both heat exchangers 104 and 106 to be coupled to the same exhaustfan (not shown), thereby simplifying the installation of the units.

[0031] Specific embodiments of the present invention have beendisclosed; however, several variations of the disclosed embodimentscould be envisioned as within the scope of this invention. It is to beunderstood that the present invention is not limited to the embodimentsdescribed above, but encompasses any and all embodiments within thescope of the following claims.

1. A heat exchanger for exchanging heat between a cooler first air flowand a warmer second air flow, the heat exchanger comprising: a heatexchanger unit having a housing containing a plurality of heat exchangerplates stacked together to form a stack, each heat exchanger platehaving four corners and an aperture located adjacent each corner, theheat exchanger plates dimensioned and configured such that the aperturesof the heat exchanger plates overlap to form a first, second, third andfourth air passageways in the stack, the heat exchanger plates furtherconfigured to form an alternating series of first and second flatparallel air chambers in the stack, the first set of air chambers beingcontinuous with the first and second air passages such that air can passbetween the first and second air passages through the first set of airchambers, the second set of air chambers being continuous with the thirdand fourth air passageways such that air can pass between the third andfourth air passageways through the second set of air chambers, the stackof heat exchanger plates further configured such that the first andsecond set or air chambers are substantially air tight such that airdoes not leak between the first and second set of air chambers, the heatexchanger unit having a first and second side, the first, second, thirdand fourth air passageways each having a first end open to the firstside of the heat exchanger unit at a first port and an opposite secondend opened to the second side of the heat exchanger unit at a secondport, the stack being further adapted such that each port may beselectively plugged by a plug member, the heat exchanger unit havingfour plug members, each plug member plugging one end of each airpassageway, first, second, third and fourth air conduits, each airconduit operatively coupled to one of the air passageways, the airconduits carrying the first and second air flows.
 2. A heat exchanger asdefined in claim 1 wherein the first and second air passageways areformed on opposite diagonal corners of the heat exchanger plates, andwherein the third and fourth air passageways are formed on oppositediagonal corners of the heat exchanger plates.
 3. A heat exchanger asdefined in claim 2 wherein the first and second air conduits are mountedto the first side of the heat exchanger unit, and the third and fourthair conduits are mounted to the second side of the heat exchanger unit,the first air conduit being operatively coupled to two of the ports onthe first side of the heat exchanger unit, the second air conduit beingoperatively coupled to the other two ports on the first side of the heatexchanger unit, the third air conduit being operatively coupled to twoof the ports on the second side of the heat exchange unit, and thefourth air conduit being operatively coupled to the other two ports onthe second side of the heat exchange unit.
 4. A heat exchanger asdefined in claim 3 wherein the heat exchanger further comprises aplurality of substantially identical heat exchanger units, each heatexchanger unit having its first side mounted to the first and second airconduits and its second side mounted to the third and fourth airconduits.
 5. A heat exchanger plate for use in forming the heatexchanger defined by claim 1, the heat exchanger plate comprising; (a) aflat substantially rectangular sheet having a flat surface, four cornersand a peripheral rim, said rim having a height, (b) a first pair ofapertures formed on the sheet, each opening having a diameter and aperipheral edge, each aperture positioned adjacent a corner of thesheet, (c) a pair of collar portions extending perpendicularly from thesheet, each collar portion positioned adjacent a corner, each collarportion having a rim defining an opening, each rim having an outsidediameter slightly smaller than the diameter of the first pair ofapertures, (d) the collar portions and the apertures positioned suchthat when two such heat exchanger plates are stacked the rims of thecollar portions of one plate extend through the first pair of aperturesof the adjacent heat exchanger plate, the collar portion being furtherconfigured such that the rim portion may be crimped around theperipheral edge surrounding the first pair of apertures to form asubstantially air tight seal.
 6. A heat exchanger plate as defined inclaim 5 wherein each collar portion is formed on the sheet and has acone shaped base, the base extending at an acute angle from the surfaceof the sheet, the base tapering to form the rim, the rim beingsubstantially cylindrical, the rim extending from the base at ashoulder.
 7. A heat exchanger plate as defined in claim 6 wherein theperipheral edge surrounding the first pair of apertures makes contactwith the shoulders of the collar portions.
 8. A heat exchanger plate asdefined in claim 7 wherein the acute angle is greater than approximately38°.
 9. A heat exchange system comprising: (a) a heat exchange unitadapted to communicate with: (i) a cool air duct; and (ii) a warm airduct; wherein said heat exchange unit comprises a plurality of heatexchange panels, the heat exchange panels being adapted to form a stackof heat exchange panels within the heat exchange unit, wherein the stackof heat exchange panels is adapted to define: (i) a first passagewaythat communicates with said the cool air duct; and (ii) a secondpassageway that communicated with the warm air duct; wherein the firstpassageway and second passageway are disposed such that the cool air inthe first passageway is adapted to be heated by the warm air in thesecond passageway.